The Bent Pyramid is a truly remarkable structure. It was built by Sneferu, father of Khufu, and is most notable for its bent shape, about halfway up, and the most intact casings of all the pyramids in Egypt. Sneferu founded the 4th dynasty, and may have finished, or even entirely built, the Pyramid at Meidum. This would give Sneferu at least three pyramids to his credit. Egyptologist have observed structural problems, which may have caused the builders to change the angle of inclination to 43°, 45 meters high, and giving the bent pyramid it's 2 angle shape. The bottom casing were laid inclined inward, at the angle change they are laid horizontally, suggesting that the builders were concerned with stability of the structure. The pyramid has 2 entrances, on one the north and another on the west face, this also is a remarkable fact. The northern entrance accessible to to the visitor, , aligns with the pyramids north-south axis, is located about 12 meters above ground level. A descending corridor behind it opens into an underground chamber whose high ceiling consists of a corbel vault of large limestone slabs. A short passageway in the southeast gives access to a vertical shaft, now partly destroyed, which in the course of archaeological investigation became known has the chimney. It is precisely aligned with the vertical axis of the pyramid. The west entrance is located much higher than the north entrance, some 30 meters above ground level. Behind it opens a descending corridor provided at two points with specially constructed barriers. It ends in the so-called upper chamber, which also has a corbel vault. Fakhry believed that Sneferu was buried in this chamber. Just south of the south side, but still on the pyramid axis, stands a small cult pyramid. The entrance, at ground level, is on the north side. It leads into a descending corridor, then ascends and comes out into a small corbel vaulted room some seven meters high. Many scholars consider this corridor to be the model for the Great Gallery in Khufu's pyramid at Giza.